I've been having this problem ever since I first installed OSX on my system. My network connection will drop out and come back for seemingly no reason. If a transfer is already in progress however it is unaffected. As an example, torrents will continue downloading while loading a web page will take 30 seconds or more to start.

My system is an Intel Bad Axe 2 board with a PentiumD 920 and 2GB of OCZ Platinum Rev.2 RAM. I am running it at 3.15GHz and the RAM at 900MHz but the problem was the same before I overclocked.

The problem has existed under 10.4.8 with Semthex's kernel and DaemonES' kernel, as well as 10.4.9 with Netkas' 8.9.1 kernel. I've tried using the onboard gigabit, a Realtek-based 8169S-32 Netgear PCI card and a Zydas-based 802.11g USB adapter, all with the same results. I've also tried replacing the IONetworkingFamily.kext with an older version from 10.4.7. As of now I'm at a loss as to what else to try. Anyone have any ideas?